Radio shielding spark plug connection



April 19, 1938. R, HS'T Ng 2,114,750-

RADIO SHIELDING SPARK PLUG CONNECTION Filed July 27, 1935 2a FIG..1.

6m INVENTOR.

/ .v, AFwLATTORNEY.

Patented Apr. 19, 1938 1:. am stonenoumiamk, N. J., assignor to Titeilex Metal Hose 00., a corporation of New Jersey Application July 2'1,'1935,'Serial No. 33,439

16 Claims. 123-469) This invention relates to the connection of i8- nition wires to the spark plugs of internal com-- bustion engines in such manner that a shield is provided to prevent interference with the operation of neighboring radio apparatus by ignition current passing through the connection. The shielding means of the connection may cooperate with other shielding means upon other portions oi the ignition system so that thewhole ignition system is shielded from interfering with neighboring radio apparatus.

ially isthis shielding necessary on areoplanes where the engine and radio are necessarily closely associated and the use of the radio is made extremely difilcult if not impossible by the interference occasioned by the operation of the ignition system of the engine unless shielding from the ignition is provided.

The main object of the invention is to provide a spark plug connection which shall have the shielding properties as referred to and also the other essential characteristics required of a spark plug connection.

A further object, of the invention is to provide a spark plug connection of the character as indicated which shall be capable of simple and inexpensive manufacturing.

A further object of the invention is to provide a structure of the character as indicated wherein the insertion and removal of the ignition wire may be readily accomplished.

A further object 0! the invention is to provide a device of the character as described wherein the on of heat from the eng ne al the 5 connection is retarded to prevent injury to the ignition connections by heat as transmitted.

Other and ancillary objects of the invention will appear hereinafter.

In the accompanying the inventiondrawing which illustrates Fig. 1 lsa central longitudinal section of a dev.

vice embodying the invention;

Fig. 2 is a similar view of a modified construction on a reduced scale;

Fig. 3 is a side elevation. on an enlarged scale. 0! an end of an ignition conductor adapted for use in the construction of Fig. 2;

Fig. .4 is a view similar to Figs. modified construction; and

1 and 2 of a Fig. 5 is a side elevation, on an enlarged scale,

of an end oi. an ignition conductor adapted for use in the construction of Fig. 4.

Referring to the drawing, and

the spark plug comprises the usual threaded outer metal casing I which is screwed into the engine block in the well-known manner and has soldered or otherwise metallically secured to it the usual sparking electrode 2. The other and central sparking electrode 3 is insulated in the usual manner by being carried in a porcelain plug 4 which is clamped in the casing I but instead of being so clamped by the usual hollow nut a hollow metal casing consisting of the end portions 5 and 6, between. which extend the strips], has its lower end portion 5 screw-threaded into the casing I and serves to clamp the porcelain plug in place. The central electrode 3 extends above the top of the porcelain where it is provided with a flat contact 8. It will be seen that the spark plug as described is of the standard and well-known type except for the modified form of nut by which the porcelain carrying the central electrode is clamped in position and the contact at the top of the central electrode. 1

' To the top portion 6 is secured a structure comprising the metal casing including the cylindrical portion 9 of copper, this copper portion havin one end It closed and the other end open. The cylindrical portion 9 has a lateral opening I I with which registersa cylindrical metal portion I2 of stainless steel, in chrome or other metal of relatively low heat conducting properties. This retards the transmission of heat from the engine back along the ignition lead while the copper portion 9, being a good dissipator or radiator 0! heat, acts with regard to any heat which does reach it to reduce the heat transmitted along the ignition conductor. The portions! and I. are secured together with their axes at an angle, and in electrlcal conducting relation in any suitable manner as by brazing.

The ignition connection requires to be well insulated and accordingly a body 0'! suitable electrical insulating material I3 such as bakelite, a well-known phenolic condensation product, is molded within the metal casing and with a projection fl extending below the metal portion I2 and fitting within the end portion l. The insulation is molded about a metal tube- It located centrally oi the portion II such tube being of stainless steel or other metal of relatively low heat conducting propertiesior reasons as above referred to. To the lower end 01 the tube II is I secured by brazing or in other suitable ways, a

sulation oi the projection II. To the top of the tube I 4 is secured by brazing or in any other suitable way, a metal block IIv oi square cross section through the head and casing I, such grounding block l8, secured together are placed in position in the metal casing and the insulation molded about them. The clearance I1 is then formed. The relatively large recess [9 for the reception of the insulation wire l9 of usual construction consisting of the copper conductor 20 covered with insulation 2 I, is cored out by a core occupying the space during the molding, such core preventing the molten insulation from entering the bore 22. Also the metal block II has a lateral hole 23 registering with the tube It and opening into the bore 22. The conductor 29 from which the insulation is removed passes through the recess 22, the hole 23 and the tube I4 and thence into a slot 24 in the sleeve IS. The conductor 20 is secured by means of a set screw l6 screwthreaded in the tube and clamping the conductor against the tube I 5.

To establish electrical connection from. the conductor to the central spark plug electrode 3 a metal spring coil 8' ofphosphor bronze or other suitable material, has its upper coil sprung into the groove IS in the sleeve while its lower end is spring pressed against the contact 9.

It will be observed that the metal casing including the members 9 and I2 are grounded being desirable to the radio shielding qualities of this metal casing.

To secure the shielding casing 9 to a shielding portion extending back over the ignition wire l9 toward the magneto, an exteriorly threaded metal block is secured to the end of the metal casing portion 9 in any suitable way as by brazing, the insulated ignition conductor l9 passing therethrough. A hollow nut 26 to which the shielding casing toward the magneto is secured is screw-threaded upon the block 25 and when screwed up bears against the hollow cone-shaped metal member 21 secured in a groove in the block 25 by brazing or in any other suitable way. thereby electrically connecting the shielding casing 9 with the shielding casing closer to the magneto. This electrical connection is not, however, absolutely necessary in the present case as the casing for the connection including the parts 9 and 12 are otherwise grounded through the spark plug as before referred to.

Within the cone-shaped portion 21 is a rubber ring or washer 28 which is forced downwardly against the insulated conductor l9 as it is compressed by the screwing home of the nut 26, thereby forming a fluid-tight joint which prevents any moisture from entering the spark plug connection and also frictionally grips the insulated conductor l9 to hold it against withdrawal.

The molded insulation with its metal casing is secured in operative relation to the spark plug by means of a hollow metal nut 29 screw-threaded upon a boss 30 upon the head 6 and having an in-turnedfiange 3| overlapping a flange 32 upon the lower end of the casing part l2. When the nut 29 is screwed home the flange 32 will be clamped firmly against the boss 3|! thereby establishing a firm and stable mechanical connectlon.

It will be observed that when desired the set screw l6 may be released, and the wire readily withdrawn through the tube l4. This is an important feature in connection with the placing or renewal of ignition wires which are especially liable to-damage in connection with aeroplane engines and may require frequent renewal. If

' 2,114,760 having the bore 22. The tubes ll and liand.

the bakelite insulation were molded directly about the conductor 29 it would be practically impossible to remove it to renew the ignition lead. Where it is attempted to form a hole through the molded bakelite by using a core in the molded portion which core is to be subsequently withdrawn, it has been found to be extremely dimcult if not-impossible to remove the relatively long thin core. With the use. of the tube H, with the insulation molded about it, however, the difiiculties as referred to are avoided, the tube is held firmly in position and provides a passage through which the ignition conductor may be readily inserted or withdrawn at, will.

It will further be observed that the ignition conductor is amply insulated and that the exterior grounded metal casing provides 'a radio shielding of the connection as referred to.

Referring to Figs. 2 and 3 there is therein shown a modified construction which is similar to that of Fig. 1 except that the tube and its connected metal block which form a passage way for the ignition conductor in Fig. 1, are, according to the construction of Figs. 2 and 3, themselves relied upon to form the electrical connection. Thus in the construction of Figs.- 2 and 3 the metal casing consisting of the parts 9', III

and 12, has the insulation 13" molded within it about the tube l4 and the metal block IS, the lower end of the tube It being secured to a larger tube I5 having screw-threaded in it a screw plug Ii, there is inserted in the recess in the block IS an end 20 of the copper wire of the insulated conductor I 9", about which is helically coiled a compression spring 33, one end of the spring bearing against the washer 34 which bears against the insulation of the wire, and the other end of the spring bearing against the washer 35 through which the conductor 20 passes and is headed or peened-over at 26. If desired this conductor may be brazed to the washer 35. When the spring and conductor are inserted tightly in the recess in the metal block l8, the conductor 20, which is ordinarily somewhat flexible, will buckle or give on being inserted, so that the spring 33 will maintain good connection with the plug l8 at all times. The device of Fig. 2 is secured to the spark plug by clamping thereto 'in the manner as described in connection with Fig. 1, and connection will be established from the ignition conductor 20 through the metal block I8, metal tubes I4 and I5 to the spark plug electrode by a spring similar to 8 of Fig.- 1.

Referring to Figs. 4 and 5, the construction is similar to that of Fig. 1 except for the manner of connecting the ignition wire conductor with the spark plug electrode. To accomplish this result the metal conductor 20" of the insulated conductor I9 is bared of insulation and telescoped thereon is a cylindrical block of metal 31 having a circumferential groove 38, this block being secured upon the conductor by p'eeningover or heading the conductor 20 at 39. The connection may be still further enhanced by brazing.

In establishing the electrical connection, the wire 20" and its carried metal block 31 are inserted within the recess of the metal block I8, and the screw plug l6" carrying a long needlelike member 40 extending through the tube l4 its spirit and is not therefore limited to the structween the block and the end of the central electrode conductor, is established by a spring in the manner as set forth in connection with Fig. 1.

Instead of removing the insulation and providing a grooved cylindrical block 31 as provided in Figs. 4 and 5, the wire with its insulation on it might be continued into the recess in the metal block l8 and connection be established with the conductor by causing the needle point of the member 40 to puncture the insulation and make contact with the conductor as the plug it" is screwed up. I

While the invention has'been illustrated in what are considered :its best application it may have other embodiments without departing from tures' shown in the drawing.

What I claim is:

l. A spark plug connection comprising in combination a metal casing, insulation molded therein, electrical conductors for providing ignition connections with a spark plug extending through said insulation and means for electrically con necting said conductors with the electrode of a spark plug, said connection being adapted to receive an ignition conductor and having a metal tube about which the insulation is molded.

2. A spark plug connection comprising incombination a metal casing, insulation molded therein, electrical conductors for providing ignition connections with a spark plug extending through said insulation and means for electrically connecting said conductors with the electrode of a sparkplug, said connection being adapted to receive an ignition conductor and having a metal tube about which the insulation is molded and through which the electrical connection with the spark plug is made.

3. A spark plug connection comprising in com bination a metal casing, insulation molded therein, electrical conductors ior providing ignition connections with a spark plug extending through said insulation and means for electrically connecting said conductors with the electrode of a spark plug, said connection comprising members at an angle with each other, one of said members adapted to receive an ignition conductor and the other of said members having a tube about which insulation is molded.

4. A spark plug connection comprising in combination ametal casing, insulation molded therein, electrical conductors for providing ignition connections with a spark plug extending through said insulation and means for electrically connecting said conductors with the electrode of a spark plug, said connection comprising members at an angle with each other, one of said members adapted to receive an ignition conductor and the other of said members having a tube about which insulation is molded, said ignition conductor passing through said tube.

5. A spark plug connection comprising in combination a metal casing, insulation molded therein, electrical conductors for providing ignition connections with a spark plug extending through said insulation and means for electrically connecting said conductors with the electrode of a spark plug, said connection comprising members at an angle with each other, one of said members adapted to receive an ignition conductor and the other of said members having a tube about which insulation is molded, said ignition conductor passing through said tube and means for clamping said conductor to said tube.

6. A spark plug connection comprising in combination a metal casing, insulation molded therein, electrical conductors for providing ignition connections with a spark plug extending through said insulation and means for electrically con- '7. A spark plug connection comprising in combination a metal casing, insulation molded therein, electrical conductors for providing ignition connections with a spark plug extending through said insulation and means for electrically connecting said conductors with the electrode of a spark plug, said connection comprising members at an angle with each other, one of said members adapted to receive an ignition conductor and the other of said membershaving a tube about which insulation is molded and a member movable longitudinally of said tube for establishing connection with said ignition conductor.

,8. A spark plug connection comprising in combination a metal casing, insulation molded therein, electrical conductors for providing ignition connections with a spark plug extending through said insulation and means for electrically connecting said conductors with the electrode of a spark plug, said connection being adapted to receive an ignition conductor and having a metal tube about which the insulation is molded, a screw plug engaging with said tube and a member mounted thereon and movable longitudinally of said tube for establishing connection with said ignition conductor.

9. A spark plug connection comprising in combination a metal casing, insulation molded therein, electrical conductors for providing ignition connections with a spark plug extending through said insulation and means for electrically connecting said conductors with the electrode of a spark plug, said connection comprising members at an angle with each other, one of said members adapted to receive an ignition conductor and the other of said members-having a tube about which insulation is molded, a screw plug engaging with said tube and a member mounted thereon and movable longitudinally of said tube for establishing connection with said ignition conductor.

10. A spark plug connection elbow comprising in combination a metal casing, molded insulation therein, said elbow comprising members at an angle with each other, an insulation covered conductor, said conductor extending continuously through both of said members, both conductor and insulating cover entering within said molded insulation in one of said members and extending outside the elbow, and having the insulating cover removed from that portion of the conductor within the other member, the last mentioned mem-' bers and said molded insulation, each of said' members having openings in said molded insulation in WhlCh said conductor freely lies whereby it may be readily withdrawn from or inserted in said elbow.

12. A spark plug connection elbow comprising in combination a metal casing. molded insulation therein, said elbow comprising members at an angle with each other and a conductor extending continuously through both or said members and said molded insulation, each of said members having an opening'in said molded insulation in 'which said conductor freely lies whereby it may be readily withdrawn from or inserted in said elbow and a terminal on said elbow to which the end of said conductor is connected and means for clamping said conductor to said terminal.

14. A spark plug connection elbow comprising in combination a metal casing, molded insulation therein, said elbow comprising members at an angle with each other, an insulation covered conductor, said conductor extending continuously through both of said members, both, conductor and insulating cover entering within said molded insulation in one of saidmembers and extending outside the elbow, and having the insulating cover removed from that portion of the conductor within the other member, the last mentioned member having an opening surrounded by the molded in- Y sulation in which the conductor loosely fits whereby it may be readily inserted in and withdrawn from said opening, a terminal on said elbow to which the end of said conductor is connected and means for clamping said conductor to said terminal.

15. A spark plug connection elbow comprising conductor and .the other of said members having an opening surrounded by the moldedinsulation, a conductor electrically connected to the conductor in the other member oi. said elbow freely passing through said opening whereby it may be moved along said opening to withdraw it from or insert.

it in said opening.

16. A'spark plug connection elbow comprisin8 in combination a metal casing, molded insulation therein, said elbow comprising members at an angle'with each other, electrical conductors for providing ignition connections with a spark plug extending through said insulation and means for electricallyconnecting said conductors with the electrode of a-spark plug, one of the members. of said elbow being adapted to receive an ignition conductor and the other of said members having an opening surrounded by the insulation, a member located within and movable longitudinally of said opening for establishing connection with the conductor in the other elbow member.

R. HARRY STONE. 

